Even as Senate leaders started negotiating, the contours of a bill that now spans some 1,600 pages began to come into focus.

The Senate's combination of crop subsidies, food stamps and other farm bill programs would cost $286 billion over the next five years, according to a new Congressional Budget Office assessment. That's slightly more than previous estimates. The addition of $5 billion in related disaster programs would bring the cost of the Senate's total farm bill package to $291 billion.

The legislation largely retains subsidies for crops such as cotton, rice, wheat and corn. It offers an alternative subsidy program that provides $15-per-acre payments when farm revenues fall. It boosts fruit and vegetable purchases to provide snacks for an estimated 4.5 million schoolchildren, and it eases some food-stamp requirements.

After first threatening a veto Monday, administration officials spelled out a litany of specific complaints Tuesday. Some relate to farming and some to the budget.

The White House, for instance, said it wants subsidized growers to be able to plant fruits and vegetables on their land. Fruit and vegetable growers hope to limit this planting flexibility to a small test program in Indiana.

The administration said it also opposes the Senate's proposal to spend $1 billion over five years to purchase fruits and vegetables, and to allow food stamps to be used for buying dietary supplements.

The Senate bill also adopts a common congressional trick of hiding costs by pretending that $7 billion in food-stamp spending would be allowed to expire after five years.

"The committee's actions are clearly intended to merely mask the long-term budgetary consequences of its actions," the administration's seven-page policy statement said Tuesday.

Congressional Republicans practiced similar sleight-of-hand when they were in the majority, as with a 2001 tax cut that assumed for scorekeeping purposes that certain taxes would be reinstated after 10 years.

Potential Senate amendments, including one to increase agricultural trade with Cuba, also drew White House ire. Others, such as a high-profile amendment imposing a $250,000 limit on the amount of subsidies a farm family can receive, could incite intense debate.

Originally, senators planned to begin debating amendments Tuesday. Those plans collapsed when Reid said he feared lawmakers from both parties would start offering "very mischievous" amendments on their pet topics, from ending the estate tax to boosting children's health insurance.

Through a parliamentary maneuver, Reid was able to block further amendments and ensure that only some could get to the floor.

"Do people want to be debating the war on Iraq in this bill?" Reid asked rhetorically.

If the senators can't work out their procedural dilemma, the debate could roll over until next year.